The functioning of computers is continually defining new relationships between personnel and equipment, and between equipment components. The term "computer" has come to include a device capable of both computation and the storage and retrieval of data. Integrated systems of computers have been developed in which a central computer is provided with the functions of other computers, which are commonly referred to as peripheral devices. This is the area of concern of the present invention. Master and peripheral computers are associated with an interface system through which the devices are able to communicate with each other. These systems have become standardized, so that the computers of different manufacturers may be interrelated without extensive modification.
New fields of utility are emerging rapidly with the explosive development of the computers and their functions. A typical example is the area in which the present invention has been initially developed. This is the association of computer-controlled densitometers with the highly-automated equipment used in the processing of photographic film and prints. The many functions of the processing installation are controlled by a master computer which regulates some of its own processing variables as a function of a data received from the densitometer. The densitometer is primarily a device for detecting the density of the various colors present in a sample being processed. The detection may be based upon the transmission of light through the sample, or reflected from its surface. These units have a number of applications, and are stock items that have been marketed in some quanity. Typically, the densitometer and the control master computer of the photographic processing system have been interrelated either through the activity of a human operator, or through a semi-automated arrangement in which the operator selects certain densitometer functions which are then dumped into the master computer via the interface system when called for. The presence of the human operator obviously presents the possibility of error, as well as injecting the time factor associated with human response. The master controller must also allocate communication time and hardware to the task of prompting the operator to establish the desired densitometer parameters such as color bandwidth, function, null values, and also advice the operator of errors such as values that may be out of range. It is obvious that a fully-automated system that would eliminate the presence of the operator would be highly desireable, but the accomplishment of this has had to await the present invention, which centers in a programming of the executory computer of the densitometer which is compatible with the standard RS-232 interface system.